The goal of this pilot project is to establish feasibility and generate initial outcome data concerning the physiological and affective benefits of a group exercise training program for women with recently diagnosed metastatic breast cancer. Building upon our successful exercise program which studies the effects of exercise on women with primary breast cancer, this project will determine whether a group exercise program can be an efficacious adjunctive intervention strategy for improving the health and quality of life of metastatic breast cancer patients. Women with metastatic breast cancer who provide informed consent will participate in a course of exercise training delivered in a structured group setting three times per week for 16 weeks. Assessment of fitness, well-being, and overall quality of life will be conducted prior to, during, and upon completion of the program, with follow-up assessment continuing for an additional 8 months. The specific objectives of this proposal are: (1) to demonstrate the feasibility of women with metastatic breast cancer to participate in a structured exercise program; (2) to demonstrate the efficacy of a group exercise training program for enhancing fitness, quality of life, and psychological well-being in a group of women with metastatic breast cancer; (3) to study the effects of group exercise training on behavioral and biological parameters which may underlie the hypothesized benefits of the intervention; (4) to determine whether any observed beneficial effects of the group exercise intervention persist beyond the duration of the intervention; (5) to assess the extent to which disease-related and non-disease-related variables predict benefit from participation in the exercise intervention; (6) to assess the differences in feasibility and efficacy of this intervention which may present themselves between women with primary breast cancers and women with metastatic breast disease. Our immediate goal is to conduct a non-randomized, non-comparative trial to collect initial data concerning the feasibility and benefits of the exercise program, which, if successful, will support subsequent proposals to conduct randomized comparative trials. This project will provide important data for establishing guidelines for exercise training as a means to enhance fitness & overall quality of life for women with metastatic breast cancer.